Single gold nanostars with multiple branches as multispectral orientation probes in single-particle rotational tracking

Herein, we performed a single-particle correlation study to characterize the optical properties of gold nanostars (AuNSs) with multiple sharp branches under dark-field (DF) and differential interference contrast (DIC) microscopy, and to examine their use as multispectral orientation probes.

Morphological Characterization of Wax and Surfactant–Encapsulated Microcrystalline Cellulose for Better Dispersion

Encapsulation of cellulose with wax and surfactant is a physical way to restrict cellulose-to-cellulose attraction. Because wax is often used in the wood composite process, industrial manufacturers would not have to upgrade or add expensive equipment to handle cellulose addition. The encapsulated cellulose particles could easily be transported to composite and polymer facilities and blended in a homogeneous fashion for a multitude of products and composites. It was the objective of this study to utilize differential interference contrast (DIC) microscopy to characterize the wax and surfactant coverage and encapsulation morphology of the wax–surfactant–cellulose composite. The lengths and widths of the cellulose particles were significantly changed after encapsulation. DIC microscopy found that we could fine-tune wax coverage to control homogeneity and reduce fiber bundling during dispersion. It was found that surfactants were not necessary to enhance coverage if a 1:4 ratio of wax to microcrystalline cellulose was used. However, if more wax is desired, then surfactants may be necessary to suppress fiber bundles during dispersion.

High-throughput in-focus differential interference contrast imaging of three-dimensional orientations of single gold nanorods coated with a mesoporous silica shell

Spherical AuNRs@mSiO2 have randomly oriented AuNR cores in 3D space, which could be resolved on the same focal plane by interference-based DIC microscopy.

Characterizing the non-paraxial Talbot effect of two-dimensional periodic arrays of plasmonic gold nanodisks by differential interference contrast microscopy

Exploiting the working principle of conventional differential interference contrast (DIC) microscopy, we experimentally investigate the non-paraxial Talbot effect of two-dimensional periodic arrays of gold nanodisks (AuNDs) with a periodicity ao comparable to the excitation wavelength λ.

Density imaging of heterochromatin in live cells using orientation-independent-DIC microscopy

In eukaryotic cells, highly condensed inactive/silenced chromatin has long been called “heterochromatin.” However, recent research suggests that such regions are in fact not fully transcriptionally silent and that there exists only a moderate access barrier to heterochromatin. To further investigate this issue, it is critical to elucidate the physical properties of heterochromatin such as its total density in live cells. Here, using orientation-independent differential interference contrast (OI-DIC) microscopy, which is capable of mapping optical path differences, we investigated the density of the total materials in pericentric foci, a representative heterochromatin model, in live mouse NIH3T3 cells. We demonstrated that the total density of heterochromatin (208 mg/ml) was only 1.53-fold higher than that of the surrounding euchromatic regions (136 mg/ml) while the DNA density of heterochromatin was 5.5- to 7.5-fold higher. We observed similar minor differences in density in typical facultative heterochromatin, the inactive human X chromosomes. This surprisingly small difference may be due to that nonnucleosomal materials (proteins/RNAs) (∼120 mg/ml) are dominant in both chromatin regions. Monte Carlo simulation suggested that nonnucleosomal materials contribute to creating a moderate access barrier to heterochromatin, allowing minimal protein access to functional regions. Our OI-DIC imaging offers new insight into the live cellular environments.